
    <!DOCTYPE html>
    <html lang="zh-CN">
    <head>
      <meta charset="UTF-8">
      <meta name="viewport" content="width=device-width, initial-scale=1.0">
      <title>Zookeeper如何处理写操作和读操作？ - 交互式测验</title>
      <style>
        @import url('https://fonts.googleapis.com/css2?family=Noto+Sans+SC:wght@400;500;700&display=swap');
        
        body {
          font-family: 'Noto Sans SC', sans-serif;
          background-color: #f4f7f9;
          color: #333;
          display: flex;
          justify-content: center;
          align-items: center;
          min-height: 100vh;
          margin: 0;
          padding: 20px;
          box-sizing: border-box;
        }
        
        .main-wrapper {
            position: relative;
            width: 100%;
            max-width: 900px; /* Wider to accommodate buttons */
            display: flex;
            justify-content: center;
            align-items: center;
        }

        .quiz-container {
          background-color: #ffffff;
          border-radius: 16px;
          box-shadow: 0 8px 32px rgba(0, 0, 0, 0.1);
          width: 100%;
          max-width: 700px;
          overflow: hidden;
          z-index: 10;
        }

        .quiz-header {
          background-color: #4a90e2;
          color: white;
          padding: 20px 30px;
          text-align: center;
        }

        .quiz-header h1 {
          margin: 0;
          font-size: 24px;
          font-weight: 700;
        }
        
        .quiz-header p {
            margin: 5px 0 0;
            font-size: 14px;
            opacity: 0.9;
        }

        .quiz-body {
          padding: 30px;
        }

        .progress-bar {
            display: none; /* 隐藏进度条 */
            width: 100%;
            background-color: #e0e0e0;
            border-radius: 5px;
            height: 10px;
            margin-bottom: 20px;
        }

        #progress-indicator {
            height: 100%;
            width: 0%;
            background-color: #4caf50;
            border-radius: 5px;
            transition: width 0.3s ease;
        }

        #question-container {
          margin-bottom: 20px;
        }

        #question-text {
          font-size: 18px;
          font-weight: 500;
          line-height: 1.6;
          margin-bottom: 25px;
        }

        .options-list {
          list-style: none;
          padding: 0;
          margin: 0;
        }

        .option-item {
          background-color: #f8f9fa;
          border: 1px solid #dee2e6;
          border-radius: 8px;
          padding: 15px;
          margin-bottom: 12px;
          cursor: pointer;
          transition: background-color 0.2s ease, border-color 0.2s ease;
        }

        .option-item:hover {
          background-color: #e9ecef;
        }
        
        .option-item.selected {
            background-color: #d1e7fd;
            border-color: #4a90e2;
        }

        .quiz-footer {
          padding: 20px 30px;
          display: flex;
          justify-content: space-between; /* 将按钮分布在两侧 */
          align-items: center;
          min-height: 65px; /* Reserve space */
        }

        .nav-btn {
          background-color: #4a90e2;
          color: white;
          border: none;
          border-radius: 8px;
          padding: 10px 20px;
          font-size: 16px;
          font-weight: 500;
          cursor: pointer;
          transition: background-color 0.2s ease, transform 0.2s ease;
          box-shadow: 0 4px 12px rgba(0,0,0,0.15);
        }
        
        #next-btn {
            background-color: #28a745;
        }

        .nav-btn:hover {
          background-color: #357abd;
          transform: scale(1.05);
        }
        
        .nav-btn:disabled {
            background-color: #a0c3e8;
            cursor: not-allowed;
            opacity: 0.7;
        }

        #result-container {
            border-top: 1px solid #eee;
        }
        
        .result-box {
            border-radius: 8px;
            padding: 20px;
            margin-top: 20px;
        }
        
        .result-box.correct {
            background-color: #d4edda;
            border: 1px solid #c3e6cb;
            color: #155724;
        }

        .result-box.incorrect {
            background-color: #f8d7da;
            border: 1px solid #f5c6cb;
            color: #721c24;
        }
        
        .result-box h3 {
            margin-top: 0;
        }

        .explanation-text {
            margin-top: 15px;
            line-height: 1.7;
        }
        
        .source-text {
            font-style: italic;
            font-size: 14px;
            margin-top: 15px;
            color: #555;
        }

        
        .final-score-container {
            padding: 40px;
            text-align: center;
        }
        .final-score-container h2 {
            margin-top: 0;
            margin-bottom: 30px;
        }
        .score-summary {
            display: flex;
            justify-content: center;
            gap: 20px;
            margin-bottom: 40px;
            flex-wrap: wrap;
        }
        .score-card {
            background-color: #f8f9fa;
            border-radius: 12px;
            padding: 20px;
            width: 180px;
            box-shadow: 0 4px 12px rgba(0,0,0,0.05);
            border: 1px solid #e9ecef;
        }
        .score-card h3 {
            margin: 0 0 10px;
            font-size: 16px;
            font-weight: 500;
            color: #555;
        }
        .score-card p {
            margin: 0;
            font-size: 28px;
            font-weight: 700;
            color: #333;
        }
        .score-details table {
            width: 100%;
            font-size: 16px;
        }
        .score-details td {
            padding: 4px 0;
        }
        .score-details td:last-child {
            text-align: right;
            font-weight: 700;
        }
        .report-actions button {
            background-color: #fff;
            border: 1px solid #ccc;
            border-radius: 8px;
            padding: 12px 25px;
            font-size: 16px;
            cursor: pointer;
            margin: 0 10px;
            transition: background-color 0.2s ease, border-color 0.2s ease, transform 0.2s ease;
        }
        .report-actions button:hover {
            background-color: #f1f1f1;
            border-color: #bbb;
            transform: translateY(-2px);
        }
        .report-actions button.primary {
            background-color: #28a745;
            color: white;
            border-color: #28a745;
        }
        .report-actions button.primary:hover {
            background-color: #218838;
        }
        
        .hint-container {
            background-color: #e0f7fa;
            border: 1px solid #b2ebf2;
            border-radius: 8px;
            padding: 15px;
            margin-top: 20px;
            color: #006064;
            font-size: 15px;
            line-height: 1.6;
            display: none; /* 默认隐藏 */
        }
      </style>
    </head>
    <body>
      <div class="main-wrapper">
          <div class="quiz-container">
            <div class="quiz-header">
              <h1>Zookeeper如何处理写操作和读操作？ - 交互式测验</h1>
              <p>检验你对文档内容的理解程度</p>
            </div>
            <div id="quiz-content">
                <div class="quiz-body">
                    <div class="progress-bar">
                        <div id="progress-indicator"></div>
                    </div>
                    <div id="question-container">
                      <p id="question-text"></p>
                      <ul class="options-list" id="options-list"></ul>
                    </div>
                    <div id="result-container"></div>
                    <div id="hint-container" class="hint-container"></div>
                </div>
                <div class="quiz-footer" id="quiz-footer">
                  <button id="prev-btn" class="nav-btn">上一题</button>
                  <button id="hint-btn" class="nav-btn" style="background-color: #ffc107; color: #333; box-shadow: 0 4px 12px rgba(255,193,7,0.3);">提示</button>
                  <button id="next-btn" class="nav-btn">下一题</button>
                </div>
            </div>
          </div>
      </div>

      <script>
        const quizData = [
  {
    "question": "在Zookeeper集群中，如果一个客户端向一个Follower节点发送了写操作请求，该Follower节点会如何处理这个请求？",
    "options": [
      "拒绝该请求，并要求客户端直接连接Leader。",
      "将请求转发给Leader节点进行统一处理。",
      "直接在本地应用该写操作，并异步通知Leader。",
      "立即向所有其他Follower广播该请求以进行投票。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "根据文档描述，Zookeeper为了保证写操作的一致性，所有写请求都必须由Leader节点统一协调处理。因此，如果一个Follower节点收到了写请求，它的职责是将其转发给Leader。",
    "source": "文档中「1. 写操作的处理方式」",
    "hint": "文档中提到：'如果接收到写请求的节点不是 Leader，该节点会将请求转发给 Leader。'"
  },
  {
    "question": "根据文档，Zookeeper的Leader节点在广播一个写操作的提案（Proposal）后，必须满足什么关键条件才能最终提交该提案？",
    "options": [
      "收到超过半数（Quorum）的Follower节点的确认（ACK）。",
      "收到集群中所有Follower节点的确认（ACK）。",
      "确认提案已经成功写入所有节点的磁盘日志中。",
      "等待一个预设的超时时间，如果没有收到反对票即可提交。"
    ],
    "correctAnswerIndex": 0,
    "explanation": "Zookeeper的ZAB协议采用的是基于多数派的投票机制（Quorum）。Leader只需要获得超过半数Follower的确认，就可以认为提案已经达成共识并进行提交，这既保证了数据一致性，又避免了因少数节点故障而导致整个系统停滞。",
    "source": "文档中「1. 写操作的处理方式」下的「投票阶段」",
    "hint": "在“投票阶段”，Leader需要得到多少节点的确认才能认为提案被接受？"
  },
  {
    "question": "为什么Zookeeper的读操作性能通常远高于写操作？",
    "options": [
      "因为读操作有专用的缓存系统，而写操作没有。",
      "因为Zookeeper限制了写操作的并发数，但对读操作没有限制。",
      "因为读操作可以由任何节点直接从内存中处理，无需经过复杂的一致性协议。",
      "因为写操作需要进行磁盘I/O，而读操作完全在网络中完成。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "文档明确指出，读请求可以由任何节点（Leader、Follower或Observer）直接从其本地内存中读取数据并返回，这个过程不涉及节点间的网络通信和一致性协调。相比之下，写操作需要经过Leader转发、广播提案、半数以上节点投票确认等多个步骤，因此延迟更高，性能较低。",
    "source": "文档中「2. 读操作的处理方式」和「读操作对性能的影响」",
    "hint": "思考一下读操作和写操作的流程，哪个流程更简单，涉及的节点更少？"
  },
  {
    "question": "在读多写少的工作负载下，Zookeeper表现优异。但如果写操作变得非常频繁，哪个角色最可能成为系统的性能瓶颈？",
    "options": [
      "Follower节点，因为它们需要频繁地进行投票和数据同步。",
      "客户端，因为它需要与多个节点建立连接。",
      "Observer节点，因为它不参与投票，处理能力有限。",
      "Leader节点，因为所有写请求都必须由它来协调处理。"
    ],
    "correctAnswerIndex": 3,
    "explanation": "文档中提到，所有写请求都必须通过Leader节点处理，包括生成提案、广播、收集投票和发送提交请求。因此，在高并发写请求的场景下，Leader的负载会非常高，容易成为整个集群的性能瓶颈。",
    "source": "文档中「写操作对性能的影响」下的「Leader 的压力大」",
    "hint": "文档中写道：‘所有写请求都必须通过 Leader 处理，因此 Leader 的负载较高...’"
  },
  {
    "question": "向Zookeeper集群中增加更多节点，对读写性能会产生什么样的综合影响？",
    "options": [
      "读操作和写操作的处理能力都会线性增长。",
      "写操作的处理能力会线性增长，但读操作的性能基本不变。",
      "读写性能都会下降，因为集群内部通信开销变大。",
      "读操作的处理能力会线性增长，但写操作的性能受限于Quorum机制，不会同等增长。"
    ],
    "correctAnswerIndex": 3,
    "explanation": "文档指出，增加节点可以线性提升读操作的处理能力，因为每个节点都能独立处理读请求。然而，对于写操作，由于ZAB协议的Quorum机制，增加节点意味着可能需要更多的节点参与投票和同步，网络开销增大，因此写性能不会随节点数无限扩展。",
    "source": "文档中「3. 读写操作对性能的综合影响」下的「集群规模」",
    "hint": "考虑增加节点后，读请求是如何被分担的，而写请求的“投票”过程会发生什么变化。"
  },
  {
    "question": "关于Zookeeper读操作的一致性，以下哪个描述是正确的？",
    "options": [
      "Zookeeper保证所有读操作都是强一致性的，总能读到最新写入的数据。",
      "为了提升性能，Zookeeper的读操作允许读取到稍微“过时”的数据。",
      "只有从Leader节点读取数据才能保证强一致性，从Follower读取都是过时数据。",
      "读操作的一致性级别是可配置的，客户端可以自由选择。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "文档在“读操作对性能的影响”部分明确说明：'在 Zookeeper 中，读操作不需要强一致性，因此允许稍微“过时”的数据。' 这种设计是一种权衡，通过牺牲读的强一致性来换取极高的读性能和可扩展性。",
    "source": "文档中「读操作对性能的影响」下的「不影响一致性」",
    "hint": "文档中提到读操作的设计允许什么样的数据以换取性能？"
  },
  {
    "question": "文档中提到，Zookeeper通过哪种一致性协议来保证写操作的强一致性和高可用性？",
    "options": [
      "Paxos协议",
      "ZAB协议",
      "Raft协议",
      "两阶段提交（2PC）协议"
    ],
    "correctAnswerIndex": 1,
    "explanation": "文档在描述写操作流程时明确指出：‘这个过程通过 Zookeeper 的一致性协议（ZAB 协议）实现。’ ZAB（Zookeeper Atomic Broadcast）协议是专为Zookeeper设计的，用于在集群中实现数据的一致性和顺序性。",
    "source": "文档中「1. 写操作的处理方式」下的「广播提案（Proposal）」",
    "hint": "在描述‘广播提案’的步骤时，文档提到了一个特定的协议名称。"
  }
];
        console.log("Quiz Data:", JSON.parse(JSON.stringify(quizData))); // 添加这行用于调试，以可展开的JSON格式输出
        
        let currentQuestionIndex = 0;
        let score = 0;
        // 存储每个问题的回答状态
        const userAnswers = new Array(quizData.length).fill(null); 

        const questionTextEl = document.getElementById('question-text');
        const optionsListEl = document.getElementById('options-list');
        const resultContainerEl = document.getElementById('result-container');
        const quizContentEl = document.getElementById('quiz-content');
        const progressIndicatorEl = document.getElementById('progress-indicator');
        const prevBtn = document.getElementById('prev-btn');
        const nextBtn = document.getElementById('next-btn');
        const hintBtn = document.getElementById('hint-btn');
        const hintContainerEl = document.getElementById('hint-container');

        function loadQuestion() {
          resultContainerEl.innerHTML = '';
          optionsListEl.innerHTML = '';
          hintContainerEl.style.display = 'none'; // 隐藏提示
          
          if (currentQuestionIndex >= quizData.length) {
            showFinalScore();
            return;
          }

          updateProgress();

          const currentQuestion = quizData[currentQuestionIndex];
          questionTextEl.textContent = `(${currentQuestionIndex + 1}/${quizData.length}) ${currentQuestion.question}`;
          
          currentQuestion.options.forEach((optionText, index) => {
            const li = document.createElement('li');
            li.className = 'option-item';
            li.textContent = optionText;
            li.dataset.index = index; // Store index in a data attribute
            // 如果这道题已经回答过，恢复状态
            if (userAnswers[currentQuestionIndex] !== null) {
                if (index === userAnswers[currentQuestionIndex]) {
                    li.classList.add('selected');
                }
            }
            optionsListEl.appendChild(li);
          });

          // 如果已经回答过，直接显示结果
          if (userAnswers[currentQuestionIndex] !== null) {
              const isCorrect = userAnswers[currentQuestionIndex] === currentQuestion.correctAnswerIndex;
              showResult(isCorrect, currentQuestion);
          }
          
          updateNavigationButtons();
          updateProgress();
        }

        function selectOption(optionIndex) {
            userAnswers[currentQuestionIndex] = optionIndex;
            const currentQuestion = quizData[currentQuestionIndex];
            const isCorrect = optionIndex === currentQuestion.correctAnswerIndex;

            // 重新计算分数
            score = userAnswers.reduce((acc, answer, index) => {
                return answer === quizData[index].correctAnswerIndex ? acc + 1 : acc;
            }, 0);

            showResult(isCorrect, currentQuestion);
            updateNavigationButtons();
        }
        
        function updateProgress() {
            const answeredQuestions = userAnswers.filter(answer => answer !== null).length;
            const progressPercentage = (answeredQuestions / quizData.length) * 100;
            progressIndicatorEl.style.width = `${progressPercentage}%`;
        }
        
        function updateNavigationButtons() {
            prevBtn.style.display = 'block';
            nextBtn.style.display = 'block';
            hintBtn.style.display = 'block'; // 显示提示按钮

            prevBtn.disabled = currentQuestionIndex === 0;
            nextBtn.disabled = false; // 最后一题时，下一题按钮不禁用，而是用于显示报告
            nextBtn.textContent = (currentQuestionIndex === quizData.length - 1) ? '查看报告' : '下一题';
            
            // 如果当前问题没有提示，则禁用提示按钮并隐藏提示内容
            if (!quizData[currentQuestionIndex].hint) {
                hintBtn.disabled = true;
                hintContainerEl.style.display = 'none';
                hintContainerEl.textContent = ''; // 清除旧的提示内容
            } else {
                hintBtn.disabled = false;
            }
        }

        function showResult(isCorrect, questionData) {
            resultContainerEl.innerHTML = ''; // 清空之前的结果
            const resultBox = document.createElement('div');
            resultBox.className = `result-box ${isCorrect ? 'correct' : 'incorrect'}`;
            
            let html = `<h3>${isCorrect ? '回答正确！' : '回答错误'}</h3>`;
            if (!isCorrect) {
                html += `<p><strong>正确答案是：</strong> ${questionData.options[questionData.correctAnswerIndex]}</p>`;
            }
            html += `<div class="explanation-text">${questionData.explanation}</div>`;
            html += `<div class="source-text">来源: ${questionData.source}</div>`;
            
            resultBox.innerHTML = html;
            resultContainerEl.appendChild(resultBox);

            // 禁用所有选项的点击事件，并高亮正确/错误答案
            Array.from(optionsListEl.children).forEach((child, index) => {
                child.style.pointerEvents = 'none';
                // 高亮正确答案
                if (index === questionData.correctAnswerIndex) {
                    child.classList.add('correct'); // 需要添加CSS样式
                    child.style.backgroundColor = '#d4edda';
                    child.style.borderColor = '#c3e6cb';
                }
                // 如果选错了，高亮错误选项
                if (!isCorrect && index === userAnswers[currentQuestionIndex]) {
                    child.classList.add('incorrect'); // 需要添加CSS样式
                    child.style.backgroundColor = '#f8d7da';
                    child.style.borderColor = '#f5c6cb';
                }
            });
        }

        function goToNextQuestion() {
            if (currentQuestionIndex < quizData.length - 1) {
                currentQuestionIndex++;
                loadQuestion();
            } else {
                showFinalScore();
            }
        }

        function goToPreviousQuestion() {
            if (currentQuestionIndex > 0) {
                currentQuestionIndex--;
                loadQuestion();
            }
        }
        
        function showHint() {
            const currentQuestion = quizData[currentQuestionIndex];
            if (currentQuestion.hint) {
                hintContainerEl.textContent = currentQuestion.hint;
                hintContainerEl.style.display = 'block';
            } else {
                hintContainerEl.style.display = 'none';
            }
        }

        function showFinalScore() {
            document.querySelector('.quiz-body').style.display = 'none';
            document.getElementById('quiz-footer').style.display = 'none';

            const correctCount = score;
            const totalQuestions = quizData.length;
            const answeredCount = userAnswers.filter(a => a !== null).length;
            const wrongCount = answeredCount - correctCount;
            const skippedCount = totalQuestions - answeredCount;
            const accuracy = totalQuestions > 0 ? Math.round((correctCount / totalQuestions) * 100) : 0;
            const errorRate = totalQuestions > 0 ? Math.round((wrongCount / totalQuestions) * 100) : 0;

            const finalScoreHtml =
                '<div class="final-score-container">' +
                '<h2>答题报告</h2>' +
                '<div class="score-summary">' +
                '<div class="score-card">' +
                '<h3>得分</h3>' +
                '<p>' + correctCount + ' / ' + totalQuestions + '</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>正确率</h3>' +
                '<p>' + accuracy + '%</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>错误率</h3>' +
                '<p>' + errorRate + '%</p>' +
                '</div>' +
                '<div class="score-card score-details">' +
                '<table>' +
                '<tr><td>正确</td><td>' + correctCount + '</td></tr>' +
                '<tr><td>错误</td><td>' + wrongCount + '</td></tr>' +
                '<tr><td>未答</td><td>' + skippedCount + '</td></tr>' +
                '</table>' +
                '</div>' +
                '</div>' +
                '<div class="report-actions">' +
                '<button id="review-btn">回顾测验</button>' +
                '<button class="primary" onclick="location.reload()">再试一次</button>' +
                '</div>' +
                '</div>';

            let reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }
            quizContentEl.insertAdjacentHTML('beforeend', finalScoreHtml);
            document.getElementById('review-btn').addEventListener('click', reviewQuiz);
        }

        function reviewQuiz() {
            const reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }

            document.querySelector('.quiz-body').style.display = 'block';
            document.getElementById('quiz-footer').style.display = 'flex';
            
            currentQuestionIndex = 0;
            loadQuestion();
            updateNavigationButtons(); // Ensure nav buttons are correctly displayed
        }

        // Event Delegation for options
        optionsListEl.addEventListener('click', (event) => {
            if (event.target && event.target.matches('li.option-item')) {
                // Check if the question has already been answered
                if (userAnswers[currentQuestionIndex] === null) {
                    const selectedIndex = parseInt(event.target.dataset.index, 10);
                    selectOption(selectedIndex);
                }
            }
        });

        prevBtn.addEventListener('click', goToPreviousQuestion);
        nextBtn.addEventListener('click', goToNextQuestion);
        hintBtn.addEventListener('click', showHint);
        
        // 初始加载
        loadQuestion();
      </script>
    </body>
    </html>
  